Searching for family members using travel and immigration records

Searching for family members using travel and immigration records

I'm wondering if there is someone that can give me tips on how to find my Great Great Grandfather's parents using the travel and immigration records I have found for him.

What I have :

Passenger list

Naturalization Record ( I think it's his)

What I've found out:

1900 census says he arrived in 1887, arrival documents say 1988He was 16 or 17 when he arrivedTraveled on ship City of BerlinDeparture Liverpool England, and Queenstown Ireland (County Cork)Arrival Port of New York, New York

What my family has told me:

He arrived in NY when he was 17. We have some family from County Cork. Not sure if he came with family.

What I want to find out :

Did he arrive in NY alone ?What are his parents names ?Where did he come from in Ireland?

What I've done so far :Searched for more passenger lists/manifest records to see if some where on the documents his parents or other family members were listed. I have not been able to find anyone who came with him. I've been searching for his parents names using these documents, because I don't have anything else to go on. I don't know where he was born in Ireland. Just that he was born in Ireland. I don't know when he died, but I have a guess where he could be buried although findagrave.com did not return any results.

I've searched for the ship termsCity of Berlin, Berlin, SS Berlin, SS City of Berlin, Inman Line .I've searched for these ship names out of Liverpool, and Queens town, and arriving in Port of New York and Ellis Island.

I've used various websites includingstevemorse.org

familysearch.org

ancestry.com

rootsweb.com

immigrantships.net

findmypast.co.uk

olivetreegenealogy.com

irishtimes.com

telusplanet.net

archives.gov

ellisisland.org

castlegarden.org

I don't know what else to do or search ? Sometimes I think I'm searching incorrectly.